1. Field of the Invention
The present invention relates to an ink jet recording apparatus that records on a recording medium by discharging ink, and a method for recovering an ink jet recording head. More particularly, the invention relates to an ink jet recording apparatus provided with means for cleaning the surface of discharge openings of an ink jet recording head, and also, relates to a method for recovering the recording head thereof.
2. Related Background Art
Conventionally, a recording apparatus that records on paper, cloth, plastic sheet, OHP sheet, or the like (hereinafter, may also be referred to simply as a "recording sheet") is generally proposed as a recording apparatus having a mode in which it can mount a recording head of various recording types, such as wire-dot, thermosensitive, thermal transfer, or ink jet.
Of these recording apparatuses, a recording apparatus of the ink jet recording type (hereinafter referred to as an "ink jet recording apparatus") that records on a recording sheet by discharging ink from discharge openings, namely, nozzles, is arranged to adopt non-impact recording method having a lesser amount of noises, and also, it is arranged to perform recording operations in high density at high speeds.
Generally, an ink jet recording apparatus comprises means for driving a carriage mounting a recording head on it; conveying means for conveying a recording sheet; and control means for controlling these driving means and conveying means.
On the other hand, as energy generating devices that generate energy to be utilized for discharging ink from the ink discharge openings of the recording head, there are such devices as piezoelectric or some other electromechanical transducing devices, devices irradiating laser or some other electromagnetic waves to generate heat to be applied when discharging ink droplets, or electrothermal transducing devices having heat generating resistors for heating liquid, among some others.
Of these devices, the recording head of ink jet recording type, which discharges ink droplets by the utilization of thermal energy, is capable of recording in high resolution, because this type of the head enables the ink discharge openings to be arranged in high density. Of the heads of this type, the ink jet recording head that uses electrothermal transducing devices as energy generating devices is particularly effective in making the head smaller not only because it is possible to fully utilize for its manufacture the advantages of the IC technologies and micro-machining technologies and techniques whose advancement and reliability have been enhanced remarkably in the field of semiconductor industry of late, but also, because it is easier to assemble the head in high density at lower costs of manufacture.
As described above, the ink jet recording type is the one that can be made with simpler structures, and demonstrates excellent performance. On the other hand, however, this type has several problems yet to be solved.
At first, one of such problems is the stains that adhere to the surface where ink discharge openings are arranged for the ink jet recording head (hereinafter referred to as the "surface of discharge openings"). The stains are caused mainly by two factors. One of them is brought about by the adhesion of a part of the ink droplets which have been discharged for printing and impacted upon a recording sheet but rebounded to the surface of the discharge openings without adhering to the recording sheet, and also, by the adhesion of the fine ink droplets to the surface of discharge openings, which have been discharged but caused to float in the atmosphere besides the main ink droplets as ink is being discharged for recording. The other factor is brought about by the ink droplets remaining on the surface of discharge openings when the cap is removed from this face after having sucked ink in the ink paths or the like that conductively connect with the discharge openings or ink in the vicinity thereof when the cap is closely covered on the surface of discharge openings for the performance of recovery operation to prevent the clogging of the ink discharge openings.
If unwanted ink droplets adhere to the circumference of the ink discharge openings, there occurs the so-called "twist" that causes the direction of ink discharges to be deviated or the so-called "non-discharge" that causes the ink discharge to be disabled, hence resulting in the degradation of printing quality.
As means for solving the problems described above, there is often used a method for wiping the surface of discharge openings of an ink jet recording head with a blade (that may also be referred to as a "wiper") formed by rubber or some other elastic material (hereinafter referred to as "wiping"). As the wiping method, there are such ones in which the surface of discharge openings are allowed to be in contact with a stationary blade when the recording head is scanned or the blade moves in parallel with or rotates around the stationary recording head to be in contact with the surface of discharge openings. In order to allow the recording head to scan, the main scanning operation is most often utilized for recording. In other words, this scanning makes it possible to perform the wiping only when it is needed if only the blade is arranged to be able to advance to or retract from the position that is overlapped with the scanning position of the recording head. Also, in order to allow the blade to scan, it should be arranged to enable the blade to reciprocate in the direction orthogonal to the main scanning direction by means of the parallel advance or rotation of the blade. In this case, the ink jet recording head is arranged to be able to advance to or retract from the scanning position of the blade, hence making the wiping possible only when it is needed. In other words, if the wiping should be made only in the forward operation, the ink jet recording head is retracted in its returning operation. In this manner, it becomes possible to prevent the contact between the blade and ink jet recording head from being made more than necessary.
Further, in order to maintain the performance of the blade operation, it is most desirable to remove ink that adheres to the blade particularly when the blade is formed by rubber or the like. Therefore, it is practiced to allow the blade to abut upon an absorbent to absorb ink or to abut upon a molded or metallic edge to scape off ink from the blade. When the wiping is performed by means of the main scanning of the ink jet recording head, a cleaning member is installed on the ink jet recording head or on a carriage that mounts the ink jet recording head on it so as to clean the blade. Also, when the wiping is performed by means of the scanning of the blade, a cleaning member is installed on a location where the blade is in contact with it immediately after the blade has wiped off the ink jet recording head.
However, as the blade passes the blade cleaner correlatively, there is a fear that the blade is caused to bend once, and then, ink remaining by adhering on the blade sprays upon the restoring operation of the blade, thus staining the interior of the ink jet recording apparatus.